Mini injector valve

ABSTRACT

A mini-injector valve having a valve seat member, a movable armature, a stator, a coil spring, and solenoid coil disposed in a magnetically permeable housing. The valve seat member has an axial passageway connected to the apex of a conical valve seat. The armature has a peripheral flange adjacent to the internal walls of the housing and an axial valve stem for engaging the conical valve seat to occlude the axial passageway. The armature is magnetically insulated from the housing by a non-magnetic bushing which coaxially supports the armature for reciprocation in the housing. The solenoid coil is wound on a plastic bobbin molded onto the stator providing excellent magnetic coupling between the solenoid coil and the stator. The coil spring cirscumscribes the armature between the peripheral flange and the bobbin, and biases the armature away from the stator and the valve stem into engagement with the conical valve seat. The mini-injector valve has a linear fluid delivery in response to electrical signals having a pulse widths down to 1.1 milliseconds.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to the field of fluid injector valves, and, inparticular, to small size, high speed, electrically actuated fluidinjector valves for inejecting fuel into internal combustion engines.

2. Prior Art

The current trend in automotive fuel control systems is toelectronically compute the fuel requirements of the internal combustionengine and provide the determined quantity of fuel to the engine throughelectrically actuated fuel injector valves. There is a concerted effortby the automotive industry to upgrade the performance capabilities ofthese injector valves, improve their reliability and reduce their costs.Currently, the fuel injector valves used in the automotive industry arelabor intensive requiring a relatively large number of machined partshaving close tolerances and require complex assembly and calibrationprocedures.

This problem was initially addressed in my co-pending patent applicationSer. No. 535,009 filed Sept. 23, 1983, now U.S. Pat. No. 4,552,371,issued Nov. 12, 1985, entitled "A Low Cost Unitized Fuel InjectionSystem". This patent application discloses an injector valve having aconical valve seat engaged by a stem valve and specifically designed toreduce the number of machined parts.

The present invention is a miniature fluid injector valve designed tofurther reduce the number of parts and to eliminate to a maximum extentthe number of parts having to be machined to close tolerances. Theresultant fluid injector is not only easier to assemble and calibrate,but also has superior operating characteristics.

SUMMARY OF THE INVENTION

The invention is a solenoid actuated fluid injector valve of the typehaving a magnetically permeable housing defining a cylindrical chamber,a valve seat member having an axial fluid passageway therethrough and aconical valve seat disposed at one end of the chamber, and a linearlydisplaceable valve stem for engaging the conical valve seat to close theaxial passageway. The injector valve is characterized by an armatureconnected to and supporting the valve stem coaxially with the valve seatmember's fluid passageway. The armature having a cylindrical body and aperipheral flange at the end of the cylindrical body adjacent to thevalve seat member. The peripheral flange has a diameter smaller than theinternal diameter of the chamber. A thin non-magnetic bushing isdisposed between the armature and the housing for slidably supportingthe armature concentric in the cylindrical chamber. A stator having anaxial portion concentric with the armature and a radial flange at theend opposite the armature is fixedly attached to the housing with theend of the axial portion spaced a predetermined distance from thearmature. A solenoid assembly having a solenoid coil and a bobbin sealedto and extending along the entire length of the axial portion of thestator. The bobbin having an end face facing the armature. A coil springcircumscribing the body of the armature between the armature'speripheral flange and the bobbin's end face for producing apredetermined force biasing the armature away from the stator and thevalve stem into engagement with the conical valve seat.

The primary advantage of the mini-injector is its fast response and highspeed capabilities. Another advantage is its simple construction and theelimination of complex machined parts which significantly reduce itsmanufacturing cost. These and other advantages of the invention willbecome more apparent from a reading of the detailed description of theinvention in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view of the mini-injector valve.

FIG. 2 is an enlarged cross section of the valve member.

FIG. 3 is an enlarged cross section of the armature assembly.

FIG. 4 is an end view of the armature assembly.

FIG. 5 is an enlarged partial cross section of the forward portion ofthe mini-injector.

FIG. 6 is a cross section of the solenoid assembly.

FIG. 7 is a rear view of the solenoid assembly.

FIG. 8 is a front view of the solenoid assembly.

FIG. 9 is a cross section of an alternate embodiment of the solenoidassembly.

FIG. 10 is a cross-sectional side view of an alternate embodiment of themini-injector.

FIG. 11 is a cross-sectional side view of the armature for theembodiment shown on FIG. 10.

FIG. 12 is a front view of the armature of FIG. 11.

FIG. 13 is a graph showing the linearity of mini-injector valve's outputas a function of excitation pulse width.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a cross-sectional view showing the details of themini-injector valve 10. The mini-injector valve comprises an externalhousing 12 made from a magnetic permeable material such as a low carbonor 400 series stainless steel. The housing 12 has a body portion 14 anda contiguous necked down portion 16. The end of the necked down portion16 is partially enclosed by an integral annular end cap 18 having a 2.5millimeter axial aperture 19. The end cap 18 forms a seat for valve seatassembly 20 as shall be described hereinafter.

To appreciate the size of the mini-injector, the length of the housing12 is only 35.6 millimeters (1.4 inches) and the diameter of the bodyportion is 15 millimeters (0.6 inches).

The housing 12 has a fluid entrance port 22 which connects the interiorof the housing with a fluid inlet tube 24. The inlet tube 24 may bewelded or brazed to the housing 12 using any of the techniques wellknown in the art. The fluid entrance port 22 and inlet tube 24 mayprovide a fluid inlet to the housing 12 through the body portion 14, asshown, or through the necked down portion 16 (not shown) as would beobvious to one skilled in the art.

The valve seat assembly 20 comprises a seat member 26 and an orificeplate 28 and shown in FIG. 2. The orifice plate 28, whose thickness isexaggerated in FIG. 2, is preferably a thin stainless steel plateapproximately 0.05 to 0.07 millimeters (0.002 to 0.003 inches) thickwith a central metering orifice 30. The diameter of the metering orifice30 may be fixed or may vary in accordance with the viscosity and/ordesired fluid injection rates. The seat member 26 has an axial fluidpassageway 32 concentric with the metering orifice 30 of the orificeplate 28 but has a larger diameter so that it has no influence over therate at which the fluid is injected through the metering orifice 30. Aconical valve seat 34 is provided at the end of the axial fluidpassageway 32 opposite the orifice plate 28. The seat member 26 alsoincludes an "O" ring groove 36 for an O ring type seal 38 as shown inFIG. 1. The valve seat assembly 20 is formed by bonding the orificeplate 28 to the seat member 26 using a high strength retaining material,such as Loctite RC/1680 manufactured by Loctite Corporation ofNewington, Conn.

A valve stem 42 of an armature assembly 40 is resiliently biased by coilspring 44 to engage the conical valve seat 34 of the seat member 26 andclose fluid passageway 32. As shown more clearly in FIG. 3, the valvestem 42 has a spherical end surface 46 which engages the conical valveseat 34 of the seat member 26. The other end of the valve stem 42 isreceived in an axial aperture 48 of an armature 50 and laser welded inplace.

The armature 50 has a peripheral flange 52, a boss 54 and anintermediate land 56. The flange 52 has a plurality of longitudinalfluid vents such as slots 58 about its periphery which permit a fluidflow past the armature assembly 40. The shoulder between the flange 52and the intermediate land 56 forms a seat for coil spring 44.

As shown more clearly in FIG. 5, which is an enlarged segment of FIG. 1,a non-magnetic bushing 60, approximately 0.1 millimeters (0.004 inches)thick, is disposed between the armature 50 and the internal surface ofthe necked down portion 16 of housing 12. The bushing 60 has a lipabutting the rear surface of the flange 52 about its periphery. Theinner diameter of bushing's lip is larger than the diameter of theintermediate land 56 and therefore does not impede the fluid flowthrough the slots 58 of the armature's flange 52. The bushing 60 is madefrom a non-magnetic material such as copper, brass, aluminum, nickel ora non-magnetic stainless steel. The bushing 60 performs a dual function,first it acts as a bushing or bearing supporting the armature assembly40 for reciprocation in the housing 12 concentric with the valve seatassembly 20, and secondly, the bushing 60 functions as a non-magneticspacer maintaining a predetermined spacing between the armature 50 andthe interior walls of housing 12. This prevents direct contact betweenthe armature 50 and the housing 12 which would otherwise result in ahigh magnetic attractive force being generated between these elements.This high magnetic force would significantly increase the slidingfriction between the armature and the housing impeding the reciprocationof the armature and increasing the response time of the mini-injectorvalve.

Alternatively, the bushing 60 may be eliminated and the peripheralsurfaces of the armature's flange 52 or the adjacent internal surface ofthe housing 12 be coated and/or plated, to a comparable thickness, witha non-magnetic material, such as copper, nickel, a plastic or a ceramic.

Referring back to FIG. 1, an integral stator/solenoid assembly 62 isdisposed in the body portion 14 of the housing 12. The stator/solenoidassembly 62 comprises a magnetically susceptible stator 64, a plasticbobbin 66 molded directly onto the stator 64, and a solenoid coil 68wound on the bobbin 66. A pair of electrodes 70, only one of which isshown in FIG. 1, are molded into the plastic bobbin 66 and areelectrically connected to the ends of the solenoid coil 68. Externalelectrical leads, such as leads 72 and 74, are individually connected tothe electrodes 70 to provide electrical power to the solenoid coil 68.

Referring to FIGS. 6, 7 and 8, the stator 64 has an axial pole 76 and anintegral sectored flange 78. The axial pole 76 has a plurality ofcircumferential grooves 80 provided along its length and an axialthreaded bore 82 provided at the end adjacent to flange 78. The flange78 has a diameter which is slightly smaller than the internal diameterof the housing's body portion 14 so that the stator/solenoid assembly 62can be slidably inserted into the housing 12 through the open end 84 ofthe housing 12. Alternatively, the axial pole 76 and flange 78 may beseparate elements welded together with holes provided in the flange 78for the electrodes 70 to pass through. As shown in FIG. 7, theelectrodes 70 pass through the open portion of the sectored flange 78and are surrounded by the structural plastic material of the bobbin 66.

The bobbin 66 is made from a structural plastic such as RYNITE 546, aglass reinforced polyester manufactured by E.I. DuPont de Nemours andCompany of Wilmington, Del., which, in the preferred embodiment, ismolded directly onto the stator's axial pole 76. The plastic material ofthe bobbin 66 fills the grooves 80 of the stator's axial pole 76 axiallylocking the bobbin 66 to the stator and forming a leak tight sealtherebetween. The bobbin's forward flange 86 has an annular recess 88circumscribing the stator's axial pole 76. The annular recess 88 is aseat for the coil spring 44.

A plurality of cutouts or notches 90 are provided about the periphery offlange 86 as shown on FIG. 8. These notches permit an unimpeded fluidflow from the inlet tube 24 to the interior of the housing's necked downportion 16 as required. If the fluid entrance port 22 and inlet tube 24provide a fluid entrance into the necked down portion of the housing 12,the notches 90 about the periphery of flange 86 are not required. AnO-ring seat 92 is formed at the opposite end of the bobbin 66 adjacentto the stator's sectored flange 78 for retaining an "O" ring 94, asshown in FIG. 1. The "O" ring 94 provides a fluid seal between thestator/solenoid assembly 62 and the housing 12 effectively sealing theopen end of housing 12.

The electrodes 70 are molded directly into the bobbin 66 and extendthrough the open portion of the stator's sectored flange 78 as shown.The rear end 96 of the bobbin 66 fills in the open portion of thestator's sectored flange 78 and provides additional structural supportto the electrodes 70.

The solenoid coil 68 is wound on the bobbin 66 with its opposite endssoldered to the electrodes 70 as shown. In the preferred embodiment, thesolenoid coil comprises approximately 300 turns of #32 wire. Theinsulation coating on the wire is preferably a fuel resistant coating toprevent deterioration when used with hydrocarbon fluids, such asgasoline or alcohol, which might otherwise dissolve the insulation.

An alternate embodiment of the stator/solenoid assembly 62 isillustrated in FIG. 9. In this embodiment, the bobbin 66 is formedseparately and not molded directly around the stator's axial pole 76.The bobbin 66 is bonded to the axial pole 76 using a high strengthbonding material 98 such as Loctite RC/680 manufactured by LoctiteCorporation of Newington, Conn. The bonding material 98 completely fillsthe axials pole's circumferential grooves 80 providing a resilient fluidtight seal between the bobbin 66 and stator 64 and locks the bobbin 66to the axial pole 76 preventing longitudinal displacement between theseelements. The electrodes 70 may be molded into the bobbin 66 aspreviously discussed relative to the embodiment of FIG. 6 or may bebonded into bores provided in the bobbin with the same bonding materialused to bond the bobbin 66 to the stator 64.

Referring to FIG. 1, the stator/solenoid assembly 62 is inserted intothe housing 12 and its position adjusted to have a predetermined spacingbetween the rear face of the armature 50 and the front face of thestator's axial pole 76. The spacing between the armature 50 and thestator's axial pole 76 is adjusted so that when the armature isretracted in response to energizing the solenoid coil 68, the valve stem42 is withdrawn from the valve seat 34 a distance sufficient so that thefluid flow through the metering orifice 30 is determined primarily bythe size of the metering orifice and trimmed to the desired flow rate bythe position of the valve stem 42 relative to valve seat 34.

The diameter of the orifice is nominally selected so that if the fluidflow were unimpeded by the position of the valve stem 42 relative to thevalve seat 34, the flow through the metering orifice 30 would beapproximately 10% greater than that required. The lift of the valve stem42 from the valve seat 34 is then adjusted with a fluid flowing throughthe orifice to obtain the desired fluid flow rate. This adjustmentcapability removes the requirement for extreme accuracy of the size ofthe orifice. In older valve designs, this type of adjustment is notpractical because slight stroke variations cause excessive changes inthe response characteristics of the valve.

The spacing between the armature 50 and stator's pole 76 is accomplishedduring assembly using a special calibration fixture. This calibrationfixture (not shown) provides for a fluid flow through the mini-injectorvalve and has a threaded shaft which is received in the threaded bore 82provided in the end of the stator 64. In the calibration procedure thesolenoid is actuated, then the threaded shaft is rotated to adjust theposition of the stator/solenoid assembly 62 until the desired fluid flowrate is obtained. After the adjustment is completed, the housing 12 iscrimped in 3 or 4 places adjacent to the stator's sectored flange 78 tolock the stator/solenoid assembly 62 in the housing. The sectored flangeis then laser welded or bonded to the housing 12 using Loctite or asimilar adhesive. The rear end of the housing 12 is then filled with apotting material 100 to complete the assembly of the mini-injector 10.

The opening and closing times of the mini-injector valve are to a largeextent determined by the force exerted by coil spring 44. Higher springforces increase the opening time of the valve and decrease the closingtime while lower spring forces produce the opposite effect. Conventionalfuel injectors used in internal combustion engines have opening timesonly slightly shorter than the minimum injection times required foraccurate flow control at low delivery rates. Typically, in minimuminjection times of these injectors range from 2.2 to 2.5 millisecondswhile the opening times are approximately 1.6 milliseconds.Consequently, small changes in the spring force, which affect theopening and closing times of the valve, will produce relatively largechanges in the fuel flow rate as the injection time approaches theminimum injection time. To overcome this problem the spring is manuallyadjusted, while the valve is operating, to calibrate the injector at lowflow rates. This is a time consuming labor intensive procedure whichincreases the cost of the injector.

In contrast, the mini-injector valve due to its smallness and the lightweight of its armature, has a very short opening time which is less thanone half of the opening time of the conventional fuel injectors.Typically, the opening time of the mini-injector valve is about 0.7milliseconds. As a result, variations in the spring force will have amuch lesser affect on the fuel flow at the minimum injection times. Oneof the novel features of the mini-injector valve is that the calibrationof the force exerted by coil spring 44 is performed prior to assemblingthe valve. This is accomplished by measuring, prior to assembly, thecompressed height at which each coil spring 44 produces the desiredforce. After this height is determined, a mating armature assembly 40and a stator/solenoid assembly 62 are selected in which the spacingbetween the armature's flange 52 and the bobbin's annular recess 88 isthe same as the compressed height of the coil spring which produces thedesired force. For this selection process, the depth of the recess 88relative to the face of the stator's axial pole 76 will be premeasuredand the stator/solenoid assemblies 62 stored according to the recordeddepth. Correspondingly, a plurality of armature assemblies 40 will bemade available to the assembler. This plurality of armatures will havedifferent distances "D", where "D" is the distance between the rear faceof the boss 54 and the rear surface of the flange 52 as indicated onFIG. 3. All the assembler has to do is select a stator/solenoid assembly62 and an armature assembly in which the sum of the distance D and thedepth of recess 88 equal the compressed height of the coil spring whichproduces the desired force. It has been found that this selectiveassembly procedure results in a fluid flow calibration at minimuminjection times which is just as accurate but less complex than thecalibration procedures used for conventional fuel injectors.

In the alternative, the distance D could always be made a little longerthan required, and the calibration adjust made by selecting a washertype spacer to be inserted between the spring and the armature's flange.

Because the calibration of the force exerted by the coil spring 44 ismade prior to assembly, there is no need to provide for any subsequentadjustment of the spring force. This permits the spring 44 to be placedforward of the stator and in a position with the housing 12 which isotherwise inaccessible for adjustment, thus saving space. In particularthe location of the spring 44 forward of the stator's axial pole permitsthe bobbin 66 to be disposed directly over the stator's pole memberreducing the gap between the stator and the solenoid coil to a minimumand enhancing the magnetic coupling between the solenoid coil and thestator's pole member. This arrangement further reduces the internaldiameter of the solenoid coil and permits the use of a smaller diametercoil wire, which in turn reduces the outside diameter of the solenoid.These factors combined to reduce the overall outside diameter of themini-injector to approximately 15 millimeters (0.6 inches).

Another advantage of placing the coil spring 44 forward of the stator isthat the coil spring will have a larger diameter and a smaller length todiameter ratio. This makes the spring more stable, increases itsdurability and reduces its tendency to buckle.

FIG. 13 is a graph illustrating the operational characteristics of themini-injector valve. As shown on the graph, the quantity of fueldelivered by the mini-injector valve is a linear function of the pulsewidth of the electrical signal activating the solenoid coil 68 for allpulse widths longer than 1.1 milliseconds. It is only for pulse widthsshorter than 1.1 milliseconds that the fluid output becomes nonlinearhaving a cut off at approximately 0.4 milliseconds.

The mini-injector is about twice as fast as a conventional fuel injectorwhose fluid output ceases to be a linear function for signals havingpulse widths less than 2.2 to 2.5 milliseconds. The faster response ofthe mini-injector is the result of faster opening and closing times ofthe valve due to the smaller size and weight of the armature assembly 40and the enhanced coupling between the solenoid coil 68 and the stator64. With a fluid pressure of 25 psi and 12 volt square wave pulses, theopening time of the mini-injector is approximately 0.7 milliseconds andthe closing time is approximately 0.5 milliseconds. Again these openingand closing times are about one-half those of conventional injectorvalves.

An alternate embodiment of the mini-injector 10 is shown in FIG. 10 inwhich a fuel inlet is provided through the stator. In FIG. 10, theelements of the mini-injector valve, which are the same as shown in FIG.1, are identified by the same numerals. Referring to FIG. 10, themini-injector has a housing 112 which has a body portion 114 and anecked down portion 116 and for all practical purposes is identical tohousing 12, except that the fluid entrance port 22 and inlet tube 24 areomitted. The valve seat assembly 20, armature assembly 40, coil spring44 and stator/solenoid assembly 62 are disposed in the housing 112having the same relationship as described with reference to theembodiment of FIG. 1. However in this alternate embodiment, the stator'saxial pole 176 has an axial extension 102 which protrudes from the endof the housing 112 and constitutes a fluid inlet tube. Accordingly, anaxial fluid passageway 104 is provided through the axial extension 102and the axial pole 176 into the interior of housing 112. The bobbin 66is molded or bonded to the stator's axial pole 176 and the solenoid coil68 wound on the bobbin 66 to form the stator/solenoid assembly 62 aspreviously described relative to the embodiment of FIG. 1.

The details of the armature 150 of the armature assembly 40 are shown onFIGS. 11 and 12. Referring first to FIG. 12, the armature 150 has aperipheral flange 152, a boss 154 and an intermediate land 156corresponding to the flange 52, boss 54 and intermediate flange 56 ofarmature 50 shown on FIG. 3. As more clearly shown on FIG. 12, armature150 also has an axial aperture 148 for receiving the valve stem 42 whichis welded therein as previously described. The axial aperture 148extends through the armature 50 and mates with the fluid passageway 104passing through the stator. The axial aperture 148 may have a neckeddown portion 106 at the end adjacent to the stator as shown, or may havethe same diameter over its entire length. A plurality of grooves 108 areprovided about the periphery of axial aperture 148 to provide for afluid flow through the armature around the valve stem 42. The grooves108 may extend entirely through the armature of may be terminated at apoint intermediate the end of the valve stem 42 and the end face of theboss 154 as shown on FIG. 11.

The operation of the mini-injector valve illustrated in FIG. 10 is thesame as previously described with reference to the embodiment of FIG. 1.The only differences between these two embodiments being the location ofth fluid input port.

Having described the mini-injector valve in detail, it is submitted thatone skilled in the art will be able to make certain changes in thestructure illustrated in the drawings and described in the specificationwithout departing from the spirit of the invention as set forth in theappended claims.

What is claimed is:
 1. A solenoid actuated fluid injector valve of thetype having a magnetically permeable housing defining an cylindricalchamber, a valve seat member having an axial fluid passageway connectedto a conical valve seat disposed at one end of said chamber and alinearly displaceable valve stem for engaging the conical valve seat toclose the fluid passageway, said housing further including an outlet,downstream of said fluid passageway, and a fluid inlet port, upstream ofsaid fluid passage, an improvement characterized by:an armatureconnected to the valve stem, said armature having a cylindrical body anda peripheral flange provided at an end of said cylindrical body, saidperipheral flange having a diameter smaller than the diameter of thecylindrical chamber; non-magnetic means disposed between said armatureand the housing for slidably supporting said armature concentrically inthe cylindrical chamber; a stator having an axial pole concentric withsaid armature and a radial flange connected to said axial pole at afirst end opposite said armature, said radial flange fixedly attached tosaid housing with a second end of said axial pole spaced a predetermineddistance from said armature; a solenoid assembly having a plastic bobbinsealed to the stator's axial pole and extending along the length of thestator's axial pole and a solenoid coil wound on said bobbin; and a coilspring circumscribing the cylindrical body of said armature between saidbobbin and said peripheral flange for producing a predetermined forcebiasing said armature away from said stator and said valve stem intoengagement with said conical valve seat.
 2. The fluid injector valve ofclaim 1 having an orifice plate disposed adjacent to said valve seatmember, said orifice plate having a metering orifice concentric withsaid valve seat member's axial fluid passageway.
 3. The fluid injectorvalve of claim 2 wherein the size of said metering orifice is selectedto produce a fluid flow rate greater than the desired fluid flow rateand wherein the predetermined distance between the armature and thestator's axial pole is selected to cause the fluid flow rate through themetering orifice to be equal to the desired fluid flow rate.
 4. Thefluid injector valve of claim 1 wherein the cylindrical chamber formedby the housing has a forward necked down portion housing the valve seatmember and said armature and a body portion housing said stator and saidsolenoid assembly.
 5. The fluid injector valve of claim 4 wherein saidhousing has an end cap partially enclosing the end of said housing'snecked down portion, said fluid injector further having an orifice platedisposed between said end cap and the valve seat member, said orificeplate having a metering orifice provided therethrough concentric withthe valve seat members axial passageway.
 6. The fluid injector valve ofclaim 4 wherein said bobbin is molded onto said stator's axial pole. 7.The fluid injector valve of claim 6 wherein said axial pole has at leastone circumferential groove longitudinally locking said molded bobbin tosaid axial pole.
 8. The fluid injector valve of claim 6 wherein saidbobbin includes a pair of electrodes connected to ends of said solenoidcoil and wherein said stator's radial flange has a cut out portionadjacent to said electrodes to provide for external electricalconnection to said electrodes.
 9. The fluid injector valve of claim 4wherein said bobbin is bonded to the stator's axial pole piece to form afluid tight seal therebetween.
 10. The fluid injector valve of claim 9wherein said bobbin includes a pair of electrodes connected to ends ofsaid solenoid coil and wherein said stator's radial flange has a cut outportion adjacent to said electrodes to provide for external electricalconnection thereto.
 11. The fluid injector valve of claim 1 wherein saidfluid inlet port is provided through the wall of said housing.
 12. Thefluid injector valve of claim 1 wherein a fluid inlet port is providedaxially through said stator.
 13. The fluid injector valve as defined inclaim 1 wherein said spacing means includes a thin non-magnetic bushingdisposed between a peripheral flange of said armature and said housing.14. The fluid injector valve as defined in claim 1 wherein said fluidinlet port is upstream of said armature and said armature includes firstflow means for communicating fluid to said fluid passageway.
 15. Thefluid injector valve as defined in claim 14 wherein said first flowmeans includes said radial flange which includes slots extendingtherethrough.
 16. The fluid injector valve as defined in 15 wherein saidfluid inlet port is proximate said bobbin, and said bobbin furtherincludes second flow means for permitting fluid to flow from said inletport to said armature.
 17. The fluid injector valve as defined in claim1 wherein said bobbin includes at least one radial flange, and saidinjector valve further includes sealing means disposed between saidradial flange and said cylindrical body.
 18. A fluid injector valvecomprising:a magnetically permeable housing enclosing a cylindricalchamber having a necked down portion, including an inner surface,partially enclosed at one end by an annular end cap and a contiguousbody portion open at an end opposite said necked down portion; a valveseat member fixedly disposed in said necked down portion adjacent tosaid annular end cap, said valve seat member having a conical valve seatconcentric with said necked down portion and an axial passageway throughsaid valve seat member; an armature assembly concentrically disposed insaid necked down portion, said armature assembly having a cylindricalbody, an integral peripheral flange provided at one end of thecylindrical body, and a valve stem extending axially from saidcylindrical body towards said conical valve seat, said peripheral flangeextending adjacent to the inner surface of said necked down portion ofthe housing; means for non-magnetically separating said armature'speripheral flange from the internal surface of said necked down portionof said housing; a stator disposed in said body portion of saidcylindrical chamber, said stator having an axial pole member and aradial flange connected to the pole member at a first end opposite saidarmature, said radial flange fixedly attached to said housing with asecond end of said axial pole member concentric with and spaced apredetermined distance from said armature; a solenoid assembly having aplastic bobbin sealed to and extending along the length of said stator'saxial pole member and a solenoid coil wound on said bobbin; a coilspring positioned between the armature's peripheral flange and theplastic bobbin for producing a force biasing said armature away fromsaid stator and said valve stem into engagement with said conical valveseat; and fluid input means for providing a fluid flow into saidcylindrical chamber, and an outlet proximate said necked down portion influid communication with said fluid input means through said axialpassageway of said valve seat member.
 19. The injector valve of claim 18having an orifice plate disposed between the annular end cap and saidvalve seat, said orifice plate having a metering orifice concentric withsaid valve seat member's fluid passageway.
 20. The injector valve ofclaim 19 wherein said orifice plate is fixedly attached to said valveseat member.
 21. The injector valve of claim 19 wherein said meteringorifice has a diameter selected to provide a fluid flow greater than thedesired fluid flow and wherein said predetermined distance between saidarmature assembly and said stator is adjusted to provide a fluid flowthrough said metering orifice equal to said desired fluid flow.
 22. Theinjector valve of claim 18 wherein the end of said valve stem engagingsaid conical valve seat is spherical.
 23. The injector valve of claim 18wherein said plastic bobbin is molded onto said axial pole member. 24.The injector valve of claim 23 wherein said axial pole member has atleast one circumferential groove filled by said molded bobbin to form afluid tight seal between said axial pole member and said bobbin and tolongitudinally lock said bobbin to said stator.
 25. The injector ofclaim 23 wherein said bobbin includes a pair of electrodes electricallyconnected to corresponding ends of said solenoid coil wherein saidstator's radial flange has a cut out section adjacent to said pair ofelectrodes to provide for external electrical connectio to said pair ofelectrodes.
 26. The injector valve of claim 18 wherein said bobbin isbonded to said axial pole member to form a fluid tight seal therebetweenand longitudinally lock said bobbin to said stator.
 27. The injectorvalve of claim 26 wherein said bobbin has a pair of longitudinalelectrodes electrically connected to corresponding ends of said solenoidcoil and wherein said stator's radial flange has a cut out sectionadjacent to said pair of electrodes to provide for external electricalconnection to said pair of electrodes.
 28. The injector valve of claim18 wherein said fluid input means is a fluid inlet port provided throughsaid housing.
 29. The injector valve of claim 18 wherein said fluidinput means is an axial fluid passageway provided through said stator'spole member.
 30. The injector valve of claim 18 wherein said means fornon-magnetically separating is a non-magnetic bushing disposed betweenthe stator's peripheral flange and the inner surface of said housing'snecked down portion.
 31. The injector valve of claim 18 wherein saidmeans for non-magnetically separating is a coating of a non-magneticmaterial provided on the peripheral surface of said armature'speripheral flange.
 32. The injector valve of claim 18 wherein said meansfor non-magnetically separating is a coating of a non-magnetic materialprovided on the internal surface of said housing adjacent to saidarmature's peripheral flange.
 33. A mini-injector valve comprising:amagnetically permeable housing defining an internal chamber having anecked down portion, and a contiguous body portion, one end of saidnecked down portion being partially enclosed by an annular end caphaving an axial aperture; a valve seat member disposed in said neckeddown portion adjacent to said annular end cap, said valve seat memberhaving an axial passageway therethrough and a conical valve seatconcentric with said axial passageway; an armature concentricallydisposed in said necked down portion, said armature having a flangeportion and a cylindrical boss; a valve stem coaxially attached to saidarmature and having a spherical end surface for engaging said conicalvalve seat; a non-magnetic bushing disposed between said armature'sflange portion and the internal surface of said necked down portion; astator disposed in said body portion, said stator having an axial polemember axially displaced a predetermined distance from said armature,and a radial flange connected to said housing to structurally supportsaid axial pole member concentric with said armature; a plastic bobbinconcentrically disposed around said axial pole member and joined theretoin a fluid tight relationship, said bobbin mating with said radialflange at one end and substantially extending the length of said axialpole member; a solenoid coil wound on said bobbin; a pair of electrodesdisposed in said bobbin connected to ends of said solenoid coil; a coilspring disposed around said armature's boss between said flange portionand said plastic bobbin for producing a force urging said armature awayfrom said stator and said valve stem into engagement with said valveseat; and fluid means including an inlet port for providing a fluid flowinto the interior of said housing between said valve seat member andsaid stator's radial flange and an outlet port in communication withsaid inlet port, disposed downstream of said axial passageway.
 34. Themini-injector valve of claim 33 wherein said fluid inlet means is aninlet port provided through said housing intermediate said valve seatmember and said stator's radial flange.
 35. The mini-injector valve ofclaim 33 wherein said fluid means includes an axial extension extendingfrom said radial flange on the side opposite said pole member andincluding an axial passageway passing through said extension and saidpole member.
 36. The mini-injector of claim 35 wherein a passageway isprovided through said armature concentric with said axial passagewaypassing through said extension and said pole member.
 37. A solenoidactuated fluid injector valve of the type having a magneticallypermeable housing defining an cylindrical chamber, a valve seat memberhaving an axial fluid passageway connected to a conical valve seatdisposed at one end of said chamber and a linearly displaceable valvestem for engaging the conical valve seat to close the fluid passageway,said housing further including an outlet, downstream of said fluidpassageway, and a fluid inlet port, upstream of said fluid passage, animprovement characterized by:an armature connected to the valve stem,said armature having a cylindrical body and a peripheral flange providedat an end of said cylindrical body, said peripheral flange having adiameter smaller than the diameter of the cylindrical chamber;non-magnetic means disposed between said armature and the housing forslidably supporting said armature concentrically in the clyindricalchamber; a stator having an axial pole concentric with said armature anda radial flange connected to said axial pole at a first end oppositesaid armature, said radial flange fixedly attached to said housing witha second end of said axial pole spaced a predetermined distance fromsaid armature; a solenoid assembly having a plastic bobbin extendingalong the length of the stator's axial pole and a solenoid coil wound onsaid bobbin; and a coil spring disposed between said bobbin and saidperipheral flange for producing a predetermined force biasing saidarmature away from said stator and said valve stem into engagement withsaid conical valve seat.
 38. The fluid injector as defined in claim 37wherein said plastic bobbin is sealed to the stator's axial pole. 39.The fluid injector as defined in claim 37 further including an orificeplate disposed between said valve seat and said housing.
 40. The fluidinjector valve as defined in claim 37 wherein said bobbin includes atleast one radial flange, and said injector valve further includessealing means disposed between said radial flange and said cylindricalbody.
 41. The fluid injector valve as defined in claim 40 wherein saidat least one radial flange of said bobbin is positioned proximate theradial flange of said stator.